The long-term objective of this proposal is to understand the acoustic and neural bases for primate vocal communications, including speech. The specific aims will: 1) examine and characterize the behavioral responses of rhesus monkeys to normal and temporally-manipulated vocal communication signals under semi-natural conditions; and, 2) study the neural responses to these vocalizations in the macaque auditory cortex. Ethological and behavioral experiments will give us valuable clues as to which acoustic parameters of vocalizations are significant to the animal, and these data can be used to inform the neurophysiological experiments. The field experiments outlined in this proposal will use a habituation-dishabituation task on semi-free ranging rhesus macaques using normal and temporally-manipulated vocalization form the repertoire of conspecific and heterospecific primates. Neurophysiological experiments will employ multi-electrodes techniques in the awake, behaving animal performing a task where they are required to discriminate between vocalizations. The responses of single neurons and neural ensembles in the primary auditory and auditory belt areas to normal and temporally-manipulated vocal signals will be quantified.